Đáp án:
`8.(x-1/2).(x^2+1/2x+1/4)-4x.(1-x+2x^2)=4x^2-4x-1`
Giải thích các bước giải:
`8.(x-1/2).(x^2+1/2x+1/4)-4x.(1-x+2x^2)`
`=8.[x.(x^2+1/2x+1/4)-1/2.(x^2+1/2x+1/4)]-(4x.1-4x.x+4x.2x^2)`
`=8.(x^3+1/2x^2+1/4x-1/2x^2-1/4x-1/8)-(4x-4x^2+8x^3)`
`=8.[x^3+(1/2x^2-1/2x^2)+(1/4x-1/4x)-1/8]-4x+4x^2-8x^3`
`=8.(x^3-1/8)-4x+4x^2-8x^3`
`=8x^3-8 . 1/8-4x+4x^2-8x^3`
`=8x^3 - 1-4x+4x^2-8x^3`
`=(8x^3-8x^3)+4x^2-4x-1`
`=4x^2-4x-1`